The diaphragm is a core component inside the steam turbine cylinder. Installed in grooves on the cylinder wall, it divides the cylinder into different steam pressure sections.
Typically, it consists of upper and lower halves, straddling the rotating shaft, which passes through its center.
This component guides steam flow, regulates steam pressure distribution, supports the stationary blades, and prevents interstage leakage, directly impacting the turbine's thermodynamic cycle efficiency and operational stability.
Steam turbine diaphragms are usually cast or welded from high-strength alloy steel. Their main structure consists of an upper and lower diaphragm halves. A shaft hole is located in the center of the diaphragm, through which the rotor shaft passes, maintaining a dynamic clearance fit. Combined with sealing devices, this reduces steam leakage.
Some models feature labyrinth-type sealing teeth on the inner ring.
These teeth create flow resistance through multi-stage annular gaps, reducing working fluid energy loss.